Based on the various random factors in the educational process of preventive medicine education, the paper attempted to make use of the stochastic process model to analyze and evaluate the teaching quality by establishing the corresponding dynamic model. The paper had proven that it was scientific and flexible to apply the stochastic process model to the teaching quality evaluation of the preventive medicine education with the examples of two medical schools about the teaching quality evaluation of the epidemiology and biostatistics. At last, the paper summarized a good many problems to the teaching quality evaluation of preventive medicine and put forward the proposal to improve the method.